Fig.1: the block diagram of the Programmable Continuity Tester. It feeds a current through the device under test (DUT) and the resulting signal is then buffered, amplified and compared with a reference voltage.
Let's face it, almost every analog and digital multimeter does have built-in capabilities for testing continuity. However, this function is somewhat limited. Most DMMs are preset to beep that little miniature buzzer inside when the continuity is below
about 40Ω or so.
Wouldn't it be nice to have a device that allows you to set this minimum continuity to anywhere between 1Ω and 100Ω? Well, that is exactly what this project does. It is accurate, reliable and works very well.
It can be used to check the resistance of all sorts of low
resistance devices: lamp filaments, motor windings, relays, switches, transformers, speakers, wiring harnesses or you name it. It's ideal for auto electrical work and a host of other applications.